The following reply was made to PR kern/15364; it has been noted by GNATS.

From: Chuck Silvers <chuq@chuq.com>
To: YAMAMOTO Takashi <yamt@mwd.biglobe.ne.jp>
Cc: gnats-bugs@NetBSD.org
Subject: Re: kern/15364
Date: Tue, 30 Aug 2005 09:25:34 -0700

 On Tue, Aug 30, 2005 at 10:53:22AM +0900, YAMAMOTO Takashi wrote:
 > > well, I was thinking it would be good to have the property that a given block
 > > is written in one I/O, since that's what the softdep code was designed for,
 > > and it'd be safer to maintain the assumptions that the softdep code makes.
 > > but you're probably right that it's not really required.
 > 
 > while block-alignment might have good aspects,
 > it can confuse pagedaemon and increase number of i/o
 > if both of active and inactive pages are in a block.
 
 could you give some details on how the pagedaemon would be confused by this?
 the pagedaemon will do the write-clustering regardless of what range is
 considered for clustering, so how does the block-alignment make things worse?
 
 
 > i'm not sure if it affects real-world performance, tho.
 
 I doubt it would make any difference.  in the common case of sequential writes,
 the ranges sent to VOP_PUTPAGES (by VOP_WRITE) are block-aligned anyway.
 only for random unaligned writes that happen to be close to MAXPHYS in size
 would we create more I/O requests than before.
 
 -Chuck